TEMPORAL CHANGES IN MYOCARDIAL PERFUSION PATTERNS IN PATIENTS WITH REPERFUSED ANTERIOR WALL MYOCARDIAL-INFARCTION - THEIR RELATION TO MYOCARDIAL VIABILITY
H. Ito et al., TEMPORAL CHANGES IN MYOCARDIAL PERFUSION PATTERNS IN PATIENTS WITH REPERFUSED ANTERIOR WALL MYOCARDIAL-INFARCTION - THEIR RELATION TO MYOCARDIAL VIABILITY, Circulation, 91(3), 1995, pp. 656-662
Background Several studies demonstrated ischemic microvascular damage
in patients with acute myocardial infarction (AMI). In this study, myo
cardial contrast echocardiography (MCE) was used to assess the tempora
l changes in myocardial perfusion after reflow and to investigate the
relation between MCE findings and myocardial viability. Methods and Re
sults MCE was performed with the intracoronary injection of sonicated
microbubbles before and shortly after coronary reflow and 1 month late
r in 45 patients with anterior wall AMI. MCE before reflow was analyze
d to determine the risk area as an area of contrast defect in the apic
al long-axis view. MCE images after reperfusion were analyzed to deter
mine peak contrast intensity, which should be in proportion to the con
centration of microbubbles within the microvasculature and in the infa
rcted and normal myocardium, and the ratio of these (PI ratio) was use
d to assess microvascular integrity. Areas of residual contrast defect
were expressed as a ratio to those of left ventricular myocardium (RC
D ratio) to assess the spatial extent of the MCE ''no reflow.'' Region
al wall motion (RWM, SD per chord) in the territory of the left anteri
or descending coronary artery was determined by the centerline method
in both the acute and late stages. Although the PI ratio was extremely
low shortly after coronary reflow, it increased in the late stage of
AMI with the improvement in regional contractile function (RWM, -3.2+/
-0.5 versus -2.6+/-1.0, P<.01; PI ratio, 0.44+/-0.25 versus 0.60+/-0.2
9, P<.01). Reduction in the RCD ratio was observed even in 15 patients
with MCE no reflow in the acute stage (0.33+/-0.09 versus 0.16+/-0.11
, P<.01). Then we investigated the relation between residual contracti
le function and microvascular integrity in the late stage. A significa
nt correlation was found between the PI ratio and RWM (r=.73, P<.001)
in the late stage of the AMI. Conclusions (1) Recovery from ischemic m
icrovascular damage is generally observed in the late stage of AMI in
association with improvement in myocardial contractile function. The d
egree of improvement in contractile function and microvascular integri
ty, however, varies among patients. (2) Contrast peak intensity in the
late stage of infarction may provide a useful estimate of myocardial
viability.